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Treatment of Traumatic Injuries

Restorative Aspects in Anterior Crown Fractures

Didier Dietschi, DMD

Stabilization, improvement, or reestablishment
of function and aesthetics in traumatized teeth (and their periodontal support)
remains a challenging endeavor, particularly when restorative procedures must
be performed in emergency situations, or within a limited period following the
trauma. Numerous lesions can occur as a result of trauma that involves the hard
tissue or -- in advanced cases -- the pulp, periodontal ligament, and bone.
Provisional and permanent treatment planning is dependent upon the extent and
severity of the dental and periodontal lesions. The long-term prognosis of
traumatized tissues requires restoration of functional integrity, tooth
vitality, and prevention of root resorption.1 This article discusses
the more frequent complications following traumatic injuries, as well as
various provisional and permanent treatment modalities for treatment of coronal
fractures.

Crown
Fractures

Crown fractures are the most common traumatic
injuries encountered in the permanent dentition. Uncomplicated injuries of the
hard dental tissues comprise enamel infraction (cracks without loss of
substance), enamel fracture, and enamel-dentin fracture (without pulp
exposure). Complicated crown fractures involve dentin and enamel with pulp exposure. Depending on the
amount of hard tooth substance loss and soft tissue involvement, different
restorative modalities have to be considered. Treatment may consist of
grinding/polishing the fractured enamel (for minimal tissue loss), dentin
sealing with or without pulp protection-capping, adhesive fragment
reattachment, direct or indirect composite build-up of the missing hard
tissues, or extended or prosthetic restoration of the tooth with veneers or
crowns.

Priority is always given
to the preservation of the pulp vitality and sealing of the dentin tubules
which, if performed adequately, may allow the final restoration of the tooth to
be delayed. When the tooth fragment is recovered, however, immediate
reattachment provides biological protection as well as the restoration. The
biological response to the trauma is related to the pulp vascularity; the risk
of pulp necrosis is significantly enhanced in situations where a concomitant
luxation injury with compromised neurovascular supply is present.

Dentin
Sealing and Pulp Capping

Due to time constraints or psychological
disturbances induced by trauma, immediate treatment requires cleansing of the
fracture line with subsequent application of a modern adhesive and thin
composite layer when no pulp exposure is present. The complete tooth
restoration is then postponed. While the risk of pulp complication is normally
minimal, in the absence of additional luxation, canal obliteration may be
subsequently observed.2-6

If pulp exposure is
evident, immediate treatment is necessary in order to reduce the exposure of
tissue to bacteria in the buccal environment. With a normal pulp status, intact
vascular supply, and absence of profuse hemorrhage prior to the trauma, the
application of pulp capping or limited amputation should be successful in the
majority of cases.1 When minimal pulp exposure and an absence of
bleeding are evident, the adhesive agent can be applied directly on the pulp
without a calcium hydroxide barrier. Pulp capping -- with or without partial
pulpotomy -- is indicated for large pulp exposure, uncontrollable hemorrhage,
or surface wetness, which prevent the successful application of an adhesive
(Figures 1-2-3-4-5-6-7).

Fragment
Reattachment

The last generation of bonding agents
facilitated the bonding and satisfactory retention of the original tooth
fragment to its initial position. To date, no other long-term provisional
restorative material can more effectively recreate or imitate the texture,
morphology, and tissue abrasion to the antagonist tooth than the natural
fragment itself. In addition to these numerous advantages, reduced chairtime is
required for fragment reattachment, which subsequently increases patient
satisfaction (Figures 8-9-10).

A holder can be used to
stabilize the fragment during restorative procedures (eg, leveling the fracture
line, conditioning the enamel and dentin of the fragment, and adhesive
application) prior to fragment fixation. While chamfer preparation has been
recommended,7 it exposes the composite layer to wear and
discoloration, which impairs the aesthetics of the repair and increases the
need for additional maintenance. Moreover, control of fragment repositioning
becomes challenging. A thin layer of color-matched or translucent composite
resin is placed with the "sandwich" technique prior to fragment
placement to ensure its stability. Scanning electron microscopy examinations
have demonstrated enhanced resin infiltration and adhesion at the interface
when composite resin was added in between (Figure 11).

Reinforcement of the
fracture line at a second intention does not prolong fragment retention.8
The fracture strength of fragments bonded with a former generation adhesive was
comparable to those of intact teeth.9 When submitted to more severe
forces, the fracture strength was reduced by 30%.8,10 Nevertheless,
increased strengths can be expected with the last generation of bonding agents
(Figures 12-13-14-15).

Immediately following
retrieval, the avulsed fragment should be stored in a humid environment (eg,
water, saliva, milk) to prevent tissue desiccation and a color shift between
the reattached piece and the remaining tooth structure. It must be noted that
the fragment may not fully recover its original color following replacement in
the oral environment. Since dentin apposition occurs at different rates,
particularly underneath the fracture line, the vital aspect of the tooth and
adjacent teeth may increase the perceived difference in color. If dentin
apposition or pulpal obliteration occur, however, bleaching procedures can be
incorporated (provided the pulp is stable).11 This concept can be
applied to composite restorations placed following trauma in the absence of
fragment retrieval.

Composite
Restoration

Current composite systems produce satisfactory
and predictable aesthetic results (Figures 16-17-18-19-20-21-22-23).12-17 For
natural aesthetics, a silicone reference device obtained following fabrication
of a composite mock-up will facilitate the correct placement of various
increments of composite resin to control restoration form, color, and opacity.13,17
The use of different masses with specific colors, chroma, and opacities
facilitates the development of internal shading and superficial light effects --
particularly in the incisal third -- to replicate natural aesthetics. Finishing
and polishing are the final, crucial steps required to develop or refine the
form and function, as well as to create the surface texture.

The ratio between the
free and bonded restoration surface (configuration factor) is extremely
favorable in the case depicted in figures 21 through 23, and subsequently
facilitated achievement of a stable marginal integrity.18 Evidence
of wear, discoloration, or restoration debonding indicate the need for
replacement, and should -- in case of premature failure -- be attributed to
improper composite material selection, adhesive agent, and placement
techniques.

With the exception of
severe loss of tooth structure, indirect techniques should not be considered
for the treatment of young patients (under the age of 20 to 25), simply because
they provide superior initial aesthetics. The preparations required for veneer
or full-coverage crown restorations are considerably more invasive than the
fracture line cleaning and tooth restoration with composite (in combination
with bleaching procedures involved in direct treatment). In addition, the
tooth's biomechanical integrity is subsequently compromised in indirect
treatment. It is, therefore, highly recommended to allow full tissue maturation
prior to treatment, following stabilization of the gingival profile and
reduction of the pulpal volume.

Ceramic
Restorations

Partial tooth coverage demonstrated advantages
over full-tooth coverage with either a porcelain-fused-to-metal or all-ceramic
crown restoration (Figures 24-25-26-27). Aesthetics, biological response, and
absence of restoration interference with the periodontium justify the increased
interest in this treatment approach. Placement of a ceramic veneer or a
full-coverage crown restoration is not immediately indicated. This treatment
modality is considered primarily for adult patients following an adequate
observation period. A direct composite restoration will generally assume the
pulpo-dentin protection, function, and aesthetics during the provisional phase.

The long-term cumulated
expense of restoration replacement must also be considered, and this element
must be integrated in the treatment planning process.19 Additional
expenses can also develop from the correction of common prosthetic treatment
"complications" (eg, gingival retraction or loss of tooth vitality)
after tooth preparation and full-coverage crown placement. These aspects
support the selection of more conservative adhesive procedures (eg, direct
restorations or veneers).

Crown-Root
Fractures

If the fracture extends below the gingiva, the
severity of the trauma is increased, and treatment is subsequently complicated.1,20
The two types of situations that can be encountered are 1) the fracture line
violates the biologic width yet extends close or only slightly beneath the bone
level, facilitating conservative treatment modalities, or 2) the fracture line
extends further apically and requires extraction or forced orthodontic eruption
(prior restoration, extraction, and implant or fixed partial denture
placement).

Following fragment
removal, the extent of the fracture line, as well as the shape and length of
the remaining root will be the determinant for the multidisciplinary treatment
approach. In patients with immediate or delayed extraction, a thorough skeletal
and dental diagnosis facilitates selection of the most appropriate solution,
which might include orthodontic, periodontal, or implant surgery, as well as
subsequent restorative procedures.21-23

Luxations
Concomitant to Crown Fractures

According to studies, luxation injuries (a
dislocation of the tooth due to traumatic impact), can account for between 15%
and 61% of dental trauma to permanent teeth.24 Luxation injuries can
cause frequent complications in the crown or crown-root fractures, and may
affect the periodontal structures and the blood supply of the pulp.24
As the impact incidence resulting in a crown fracture is more perpendicular
than vertical, and since the energy of the trauma dissipates partly during the
fracture process, slight to moderate luxations are the most frequently
associated types of injuries. It must be stressed, however, that luxation
injuries can be complicated by temporary or permanent loss of marginal alveolar
bone support, which can greatly affect the prognosis of the luxated teeth.

Conclusion

Therapeutic difficulties caused by mutilated
anterior teeth and traumatic loss, as well as the rising socioeconomic expense
of dental trauma, reinforce the need to increase clinicians' knowledge of
emergency primary dental care and the multidisciplinary approach in related
restorative procedures. These restorative procedures provide predictable and
functional aesthetic results that will subsequently enhance patient
satisfaction, while improving the clinician's ability to provide optimum
service and support.